1. Field of the Invention
The present invention relates generally to the art of antireflective coatings, and more particularly to the art of multilayer antireflective coatings on glass.
2. Relevant Art
A method for attenuating the refractive index difference between a metal oxide and a glass substrate is disclosed in U.S. Pat. No. 3,378,396 to Zaromb, wherein a glass substrate is coated by simultaneously directing separate sprays of a tin chloride solution and a silicon chloride solution onto a stationary heated glass substrate in an oxidizing atmosphere, e.g. air. The heat of the glass substrate thermally converts the metal chlorides to their metal oxides. The ratio of the sprays to each other are gradually varied to vary the ratio of the weight percent of the metal oxides in the coating. The resultant coating has a continuously changing composition throughout its thickness, e.g. near the glass-coating interface, the coating is predominantly silicon oxide, the surface of the coating furthest from the glass-coating interface is predominantly tin oxide, and between the surfaces the coating is made up of varying weight percent amounts of silicon oxide and tin oxide.
U.S. Pat. Nos. 4,206,252 and 4,440,882 teach the depositing of a second coating composed of fluorine-doped tin oxide on a gradient coating such as described above.